The overall goal of this project is to conduct comparative effectiveness research on breast cancer imaging modalities and strategies to inform evidence gaps on how to optimize breast cancer screening in community practice. The Breast Cancer Surveillance Consortium (BCSC) is uniquely positioned to conduct rigorous comparative effectiveness studies on conventional and new breast imaging technologies to inform how screening strategies could be personalized based on patient demographic and risk factor information and optimize the balance of screening benefits and harms. The BCSC includes detailed longitudinal information throughout the cancer care continuum: from cancer screening and diagnosis through treatment, surveillance, and death on over 2 million women and 95,000 breast cancers. It is the only resource of this size with risk factor information (including mammographic breast density) that is also linked to: mammography examinations accurately identified as either screening or diagnostic and as either film-screen or digital;cancer registry and pathology databases to determine both benign and malignant outcomes;Medicare and Group Health managed care claims data to obtain comorbidities and healthcare utilization;and death data to ascertain vital status and cause of death. Over the next two years we will: 1) Use existing BCSC screening data with long-term follow-up (overall and breast cancer mortality) and newly linked BCSC-Medicare data to compare the clinical effectiveness of 1- vs. 2- year mammography screening intervals for subgroups of women;2) Use BCSC-Medicare data to compare the downstream healthcare utilization and costs of digital versus film-screen mammography;3) Use BCSC data in four Cancer Intervention and Surveillance Modeling Network (CISNET) breast cancer simulation models to compare the clinical and cost-effectiveness of various breast cancer screening strategies;4) Implement a prospective data collection system specifically designed to capture clinically and scientifically relevant data on breast magnetic resonance imaging (MRI) across our network of BCSC community practice facilities;5) Expand the BCSC Statistical Coordinating Center's capacity to design and conduct comparative effectiveness research in community settings by developing epidemiologic and statistical methods focused on sampling and design strategies for prospective observational and community-based randomized trials. This Grand Opportunity will increase the capacity of the BCSC and CISNET to provide evidence on how to deliver the most effective breast cancer screening in defined subgroups of women. PUBLIC HEALTH RELEVANCE: The overall goal of this project is to conduct comparative effectiveness research on breast cancer imaging modalities and strategies to inform evidence gaps on how to optimize breast cancer screening in community practice. The Breast Cancer Surveillance Consortium (BCSC) is the only resource with breast cancer risk factor information on over 2 million women linked to: mammography examinations accurately identified as either screening or diagnostic and as either film-screen or digital;cancer registry and pathology databases to determine both benign and malignant outcomes;Medicare and Group Health managed care claims data to obtain comorbidities and healthcare utilization;and death data to ascertain vital status and cause of death. We will use the BCSC infrastructure and network of mammography facilities to examine screening intervals, screening modalities, and risk factors to determine their influence on breast cancer detection and mortality and associated costs. This research will set standards and methodology for comparative effectiveness studies in community practice and enable evidence-based recommendations that maximize screening effectiveness, minimize harms of screening, and optimize healthcare utilization.